In a previously proposed solenoid valve, when a coil is energized, an armature is magnetically attracted to a stator core by a magnetic attractive force. In contrast, when the coil is deenergized, the armature is driven toward a side, which is opposite from the stator core, by an urging force of a spring. The spring is received in a spring chamber, which is formed in the stator core, and the armature is received in an armature chamber.
The armature chamber is divided by the armature into two chambers. Specifically, the armature chamber is divided into a first armature chamber, which is placed adjacent to one end surface of the armature and is communicated with the spring chamber, and a second armature chamber, which is placed adjacent to the other end surface of the armature (see, for example, JP2007-278365A).
In the case of the previously proposed solenoid valve, a pressure of the first armature chamber and a pressure of the second armature chamber are changed in response to movement of the armature, and an operational response of the solenoid valve may possibly be deteriorated by an influence of these pressures.
In order to address such a disadvantage, Japanese patent application No. 2012-4785 (corresponding to U.S. patent application Ser. No. 13/719,627) proposes formation of a communication passage, which communicates between the first armature chamber and the second armature chamber. The fluid is moved between the first armature chamber and the second armature chamber through the communication passage in response to the movement of the armature to improve the operational response of the solenoid valve.
However, in such a case, erosion may possibly be generated by cavitation at, for example, an opening end of the communication passage at the first armature chamber, and/or a wall surface of the spring chamber.